This is to clear your wallet from pending transactions. This is ONLY clearing transaction activity and clearing your wallet cache, this DOES NOT remove your transaction history. You can locate all your (polygon) transaction history at https://polygonscan.com
1) Click on your Metamask extension (circled in red and highlighted)
2) Click on the circle top-right and go to “Settings”
3) Click on the “Advanced” setting
4) Click on the “Reset Account” button
Manually editing Gas
Sometimes you need to edit gas due to the estimation being incorrect which can cause pending transactions or you would like to process a transaction faster.
1) When confirming a transaction click on the “edit” as highlighted.
2) Increase the gas price if you want the transaction to get processed faster, or the gas limit if the transaction is not being processed. Overestimating is fine, as you will only pay for what is used in the transaction.